The present invention relates to the control of a furnace with a flow sensor.
In heating systems comprising a combustion air blower and a fuel valve for providing fuel to a burner, it is generally desired to provide fuel to the burner only when proper conditions exist for flame and to maintain an optimum fuel-to-air ratio when the burner is in operation. Prior art approaches to these problems are relatively complex. Accordingly, the present invention was developed for providing control of a fuel valve in a heating system or other appliance.
Systems incorporating the present invention are typically simplified over prior art systems and may incorporate one or more of three separate and distinct features: (1) the present invention may be incorporated to allow fuel to flow only upon sensing a predetermined minimum air flow; (2) the present invention may be incorporated to modulate the fuel flow so that a fixed fuel-to-air ratio is maintained; and (3) the present invention may be incorporated to shut off fuel completely if air flow substantially ceases, such as in the case of a blocked stack or malfunctioning combustion blower. While some or all of these features are available in prior art systems, these prior art typical systems are far more complex than typical systems incorporating the present invention.